FIG. 4 is an exploded view showing a conventional electrical junction box (see PTL 1). The electrical junction box 201 shown in FIG. 4 includes: a box main body 202; cassette blocks 203A, 203B attached to the box main body 202; an upper cover (not shown) for covering an opening 202b of the box main body 202; and a lower cover (not shown) for covering an opening 202a of the box main body 202. Incidentally, the electrical junction box 201 shown in FIG. 4 is upside down with respect to an actual mounting direction on a vehicle.
The cassette blocks 203A, 203B are made of synthetic resin, and outer shapes thereof are formed in a block shape. Electronic components such as fuse or relay are mounted on an upper surface 203a of each of the cassette blocks 203A, 203B. A lower surface 203b of each of cassette blocks 203A, 203B is provided with a terminal receiving portion 231 (component receiving portion) into which a terminal attached to an end of an electric wire 208 is inserted, a bus bar receiving portion (component receiving portion) into which a bus bar is inserted, and a hollow cavity portion into which no component is inserted. Lower ends of the terminal receiving portion 231, the bus bar receiving portion, and the hollow cavity portion are aligned at the same height. Incidentally, the electric wire 208 connected to the cassette block 203A is only partially shown, and the electric wire 208 connected to the cassette block 203B is not shown.